Vaccines for other Infectious Diseases There are other illnesses, such as plague, pneumococcal disease, influenza, varicella (chicken pox), and Haemophilis influenzae type B disease, that are transmitted through infectious agents. Vaccines are currently available in the United States for each of these diseases. Vaccination for these diseases is generally less common than for some other infectious diseases because risk may be limited to persons with serious underlying medical conditions or to travelers with unusual exposure potential. Sometimes age and previous medical history are also factors in determining when to use some of these vaccines.